The disclosures of Japanese Patent Application Nos. 2001-141507 filed on May 11, 2001 and 2002-59062 filed on Mar. 5, 2002, including the specifications, drawings and abstracts are incorporated herein by reference in their entirety.
1. Field of Invention
This invention generally relates to a refresh charge control device and method. More particularly, the present invention pertains to a refresh charge control device and method for performing a refresh charge of a battery.
2. Description of Related Art
In general, when a battery is continually used under a half-charged condition which does not reach a fully charged condition, an internal material of the battery is solidified. When the internal material of the battery is solidified, the absolute capacity of the battery is reduced, and thus the duration of battery life is declined. There has been disclosed a method for regularly refreshing the battery to be the fully charged condition for preventing the decline of the duration of battery life. By regularly refreshing the battery to be the fully charged condition, the solidification of the internal material is restrained. In this manner, the battery life is ensured over the long term.
According to a system including a battery on vehicle, a period of the decline of the battery life is different depending on the individual users because the frequency for using the vehicle is different depending on the users. Despite the foregoing condition, in case the refresh charge of the battery is performed by a constant cycle (e.g., once a month) or every time the vehicle is used without considering the frequency of use by the user, the battery may be always maintained to be the fully charged condition depending on the usage by the user. In this case, the regeneration energy of the vehicle cannot be recovered to the battery, thus the mileage cannot be improved.
It is an object of the present invention to provide a refresh charge control device and method for performing a refresh charge of a battery at the appropriate period.
According to a first aspect of the present invention, the refresh charge control device includes a time count device that counts the time after achieving last fully charged condition of the battery, an accumulative electric use amount count device that counts the accumulative electric use amount of the battery after achieving the last fully charged condition of the battery, and a controller that starts the refresh charge of the battery when the time counted by the time count device and the accumulative electric use amount counted by the accumulative electric usage count satisfy a predetermined relationship.
According to the first aspect of the present invention, the refresh charge of the battery is performed when the predetermined relationship is satisfied between the time after achieving the last fully charged condition and the accumulative electric use amount after achieving the last fully charged condition of the battery. In case the time after achieving the last fully charged condition of the battery is long, it is appropriate to perform the refresh charge in order to prevent the decline of the battery life even if the accumulative electric usage of the battery is small. In case the accumulative electric usage of the battery is large even if the time after achieving the last fully charged condition of the battery is relatively short, it is appropriate to perform the refresh charge because the battery is frequently used under the half-charged condition. Thus, according to the first aspect of the present invention, when the predetermined relationship is appropriately determined, the refresh charge in accordance with the usage of the battery is performed. Accordingly, the refresh charge of the battery is performed at the appropriate period.
According to the first aspect of the present invention, the controller may start the refresh charge of the battery when the time counted by the time count device is equal to or greater than a first time and the accumulative electric use amount counted by the accumulative electric use amount is equal to or greater than a first use amount.
Further, according to the first aspect of the present invention, the controller may start the refresh charge of the battery when the time counted by the time count device is equal to or longer than a second time which is longer than the first time and the accumulative electric use amount counted by the accumulative electric use amount device is equal to or greater than a second use amount which is less than the first use amount.
According to a second aspect of the present invention, a refresh charge control device for performing the refresh charge of the battery installed on the vehicle by using a power source is provided. The refresh charge control device includes a high-speed travel judging device that judges whether the vehicle travels equal to or faster than a predetermined speed and a controller that performs the refresh charge of the battery when it is judged that the vehicle is traveling equal to or faster than the predetermined speed by the high-speed travel judging device.
According to the second aspect of the present invention, the refresh charge of the battery is performed when the vehicle is traveling equal to or faster than the predetermined speed. Because the power source of the vehicle is efficiently operated when the vehicle travels equal to or faster than the predetermined speed, the fuel efficiency of the vehicle is not significantly declined even if the battery is charged using the power source. Thus, according to the present invention, the refresh charge of the battery is performed at the appropriate period during which the mileage of the vehicle is not significantly declined.
When the condition that the vehicle travels equal to or faster than the predetermined speed continues over the long term, it is judged that the vehicle is traveling on a road such as expressway on which the high-speed traveling is achievable. Thus, in this case, the regenerative braking is hard to be performed, the generation of the regeneration energy amount is relatively small, and the opportunity for charging the battery is few.
Accordingly, according to the second aspect of the present invention, when the refresh charge control device includes a time judging device that judges whether the condition that the vehicle travels equal to or faster than the predetermined speed continues by the high-speed travel judging device and the controller starts the refresh charge of the battery when it is judged that the condition that the vehicle travels equal to or faster than the predetermined speed continues for the predetermined time by the time judging device, the refresh charge is performed under the condition that a normal charge of the battery is hard to be performed. Thus, the generation of the unnecessary energy which cannot be recovered at the refresh charge can be prevented.
When the refresh charge is frequently repeated regardless of the situation that the battery is not frequently used, the battery is deteriorated to decline the duration of battery life.
According to the second aspect of the present invention, when the refresh charge control device includes an accumulative electric use amount judging device that judges whether the accumulative electric use amount of the battery after achieving the last fully charged condition of the battery is equal to or greater than a predetermined amount and when the controller starts the refresh charge of the battery when it is judged that the accumulative electric use amount is equal to or greater than the predetermined amount by the accumulative electric use amount judging device, the deterioration of the battery is restrained.
According to the second aspect of the present invention, when the refresh charge control device includes a time count device that counts a time after achieving the last fully charged condition and an accumulative electric use amount count device that counts the accumulative electric use amount of the battery after achieving the last fully charged condition of the battery and when the controller starts the refresh charge of the battery when the time counted by the time count device and the accumulative electric use amount counted by the accumulative electric use amount count device satisfy a predetermined relationship, the refresh charge of the battery can be performed at an appropriate period in accordance with the usage of the battery without significantly deteriorating the mileage of the vehicle.
According to the construction in which the refresh charge of the battery is performed when the vehicle travels equal to or faster than a predetermined speed, provided that the refresh charge is cancelled immediately after the decline of the vehicle speed slower than the predetermined speed, the time for charging is not ensured and is hard to complete the refresh charge.
Thus, according to the second aspect of the present invention, by determining the controller to continue the refresh charge until establishing a predetermined condition even when the vehicle is not to be judged to travel equal to or faster than the predetermined vehicle speed by the high-speed travel judging device after starting the refresh charge of the battery, the completion of the refresh becomes easier to be achieved.
In this case, according to the second aspect of the present invention, the predetermined condition may include a discharge demand of the battery.
According to the second aspect of the present invention, by determining the predetermined condition is that the vehicle travels equal to or less than a vehicle speed which is equal to or slower than the predetermined vehicle speed by a predetermined value, the completion of the refresh charge is easier to be achieved while restraining the decline of the mileage of the vehicle to a minimum.
Because the discharge cannot be performed during the process that the refresh charge of the batter is performed, the operation of the electric load cannot be ensured when the refresh charge is continued regardless of the discharge demand of the battery for operating the electric load.
Accordingly, in each aspect of the present invention, by determining that the controller interrupts the refresh charge when the discharge demand is performed after starting the refresh charge of the battery and restarts the refresh charge when the discharge demand is released, the battery can be appropriately discharged even after the start of the refresh charge, and thus the operation of the electric load can be ensured.
In this case, according to each aspect of the present invention, when the refresh charge control device includes a charge accumulative time judging device that judges whether the accumulative time performing the refresh charge after starting the refresh charge of the battery is equal to or longer than a predetermined time and when the controller judges that the accumulative time is equal to or longer than the predetermined time by the accumulative time judging device after starting the refresh charge of the battery, the refresh charge may be completed.
Provided that the refresh charge of the battery is performed with a charge voltage the same with the case of the normal charge by the regenerative braking, the charging time for achieving the fully charged condition is elongated, and the effect of the refresh charge cannot be ensured promptly. On the other hand, because the frequency of the execution of the refresh charge is fewer than the frequency of the execution of the normal charge, the deterioration of the battery due to the overcharge is hard to be generated even when the battery is charged by impressing the high voltage for performing the refresh charge.
Accordingly, in each aspect of the present invention, when the refresh charge control device includes a charge voltage change device that changes the charge voltage when performing the refresh charge of the battery compared to the charge voltage when performing the normal charge, the charge voltage at the refresh charge is determined to be higher than the charge voltage at the normal charge. Thus, the deterioration of the battery due to the charging of the battery can be restrained to be the minimum and the effect of the refresh charge can be ensured in short time.
The lower the temperature is, the harder charging the battery and the higher the temperature is, the easier charging the battery. Accordingly, in each aspect of the present invention, by determining that the charge voltage change device changes the charge voltage at the refresh charge of the battery in accordance with the temperature of the battery, the effect of the refresh charge can be always achieved in short time without being influenced by the temperature of the battery.
According to each aspect of the present invention, by including a battery temperature judging device that judges whether the temperature of the battery is equal to or lower than a predetermined temperature and a battery warm-up device that warms up the battery before the start of the refresh charge when it is judged that the battery temperature is equal to or lower than the predetermined temperature by the battery temperature judging device, the refresh charge is performed effectively because the refresh charge is performed after the battery is warmed up.
In this case, according to each aspect of the present invention, the battery warm-up device may warm up the battery by operating a heating device that warms up the battery or by repeating the charge and discharge of the battery.